A pressure sensitive adhesive has viscosity at room temperature and has adhesion upon application of a light pressure without activation of heat, water, a solvent, or the like. Further, the pressure sensitive adhesive shows a strong holding force after being attached and can be removed without leaving residue. Furthermore, the pressure sensitive adhesive has many advantages including adhesiveness and elasticity. Thus, it has been widely used in various fields.
As the pressure sensitive adhesive, a rubber-based adhesive using natural rubber or synthetic rubber, an acryl adhesive, a silicon adhesive, or the like are known. The acryl adhesive is optically transparent and has a high weather resistance or a high resistance to oxidation. Thus, it has been applied in various fields.
The acryl adhesive can be classified into a solvent-based adhesive, a water-based adhesive, a hot melt adhesive, a radiation-curing adhesive, or the like. Typically, the acryl adhesive is manufactured by chemically cross-linking an acryl polymer as an adhesive resin with a cross-linker or the like. However, in a chemically cross-linked adhesive, there tends to be a tradeoff between a hardness property of the adhesive and other properties such as a tacking property or a peeling property. Thus, it is not easy to adjust all properties to be as required.